Conventional fireplaces are not very effective sources of heat for the room in which they are located. The main reason for this inefficiency is that the fire draws heated air from the room and large amounts of outside air into the house to meet the combustion requirements of the fire. This causes drafts of cold air along the floor of the room and the cooling of the house.
It is the general object of the invention to provide an air supply distributor for fireplaces designed so that the fireplace can be operated in a manner to minimize the amount of air drawn from the room to feed the fire and to increase the efficiency of the fire in heating the room.
Briefly stated, the air supply distributor in accordance with the invention is adapted for use with a fireplace provided with means for supplying relatively cold air to an opening in the hearth of the fireplace. The air supply means may comprise a flow passageway including the ash pit opening in the hearth with the air being supplied from the basement or other house area whereby relatively cold air is supplied to the fire. Alternatively, the ash pit opening may be supplied air from the outside of the house by way of suitable ductwork or other passageway means connected through a vent to the outside.
The air flow distributor of the invention is adapted to be positioned beneath the support for the combustible products and to overlie the hearth opening. The distributor comprises a pair of side walls extending from the back wall of the combustion chamber of the fireplace toward the front opening thereof and a top cover extending across the hearth between the side walls and spaced from the combustible products support. An air flow discharge opening is defined by the front edges of the side walls and top cover of the distributor and is located to face the front opening of the combustion chamber of the fireplace. The distributor is constructed and arranged to be positioned in an air flow distributing position to direct the flow of air passing through the hearth opening toward the front opening of the combustion chamber for discharge through the discharge opening from which the air passes to the fire to meet the combustion requirements thereof and upwardly through the chimney flue.
By reason of the above described arrangement, relatively cold air is supplied to the fire to support the combustion thereof thereby substituting this cold air for the room air which conventional fireplaces utilize to feed the fire. Thus, since the room air is heated by the home's heating system, the use of much less room air to feed the fire results in considerable savings in energy.
By reason of the above-described air distributor of the invention, the air is directed to flow underneath the fire and is delivered into the fireplace at a location forwardly of the fire. This arrangement avoids the danger of a "forging effect" that would occur if the air passing through the hearth opening could pass directly upwardly. The effect would probably result in a burnout of a localized section of the fire and would eventually damage the log holder or fireplace grate or whatever device is used to support the combustible products. In accordance with the invention, the inflow of air from the hearth opening to the fire is properly distributed to avoid this problem.
A further object of the invention is to provide an air distributor design that minimizes the friction loss of the supply air as it flows to the fire, i.e., to provide an air flow path having a minimum of restriction to flow. To this end, the top cover is inclined downwardly from the rear of the fireplace to the front opening thereof.
Another object of the invention is to provide an air flow distributor of the indicated type which can be manufactured in an economical manner.
Another feature of the air distributor of the invention is that it can be made of a relatively light gage sheet material since it does not have to support heavy logs or other combustible products and can be used in conjunction with existing fireplace grates or log holders.
A further feature of the air distributor of the invention is that it is designed so that it can be used with existing fireplaces provided with glass fronts and functions whether the glass doors are open or closed.
It is to be noted that the air flow distributor of the invention will control the air flow in a way to minimize the entrance of room air into the fireplace and also to minimize the passing of smoke out of the fireplace while increasing the heat output of the fireplace by reflecting or directing into the room the radiant energy of a coal bed which accumulates on the inclined top cover of the air distributor.
A further feature of the air distributor of the invention is that it serves to increase the comfort of the room's inhabitants by eliminating cold drafts that normally would accompany the infiltration of make-up air into the room to feed the fire as is the case in conventional fireplaces.
Another type of air distributor in accordance with the invention is constructed in the form of a hood perforated throughout with holes and adapted to be positioned beneath the support for the combustion products to overlie the hearth opening. This type of distributor prevents the "forging effect" described above by dispersing the supply air around the fire and achieves many of the features of the invention discussed heretofore.
Prior art fireplace air control devices are disclosed in U.S. Pat. Nos. 2,375,318; 2,470,430; and 2,819,711.